Garai, Mrinmoy and Karmakar, Basudeb (2020) Zr+4-controlled nucleation and microstructure in Si-Mg-Al-K-B-F glass-ceramic sealant (solid oxide fuel cell). Materials Today Energy, 18. Art No-100535. ISSN 2468-6069

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This work illustrates the strong effects of Ti4+ and Zr4+ (M4+) on nucleation ability of SiO2-MgO-Al2O3-B2O3-K2O-F glass-ceramic sealant. An addition of such 5 wt.% M4+ content caused a slight increase in density value (2.60-2.61 X-ray diffraction (XRD) experiment revealed no indication of any crystallinity in melt-quenched glass-sealant and that was further confirmed from transmission electron microscopy. XRD established the development of multicrystalline phases in investigated glass-sealants at solid oxide fuel cell (SOFC) operation temperature (=800 degrees C). The reflected XRD peaks on the heat treated (i.e., 800 degrees C) SiO2-MgO-Al2O3-B2O3-K2O-F glasses were indexed as norbergite (Mg2SiO4 center dot MgF2), humite Mg7F2(SiO4)(3)], chondrodite Mg5F2(SiO4)(2)], mullite (3Al(2)O(3)center dot 2SiO(2)) and enstatite (MgSiO3) phases. Field-emission scanning electron microscope (FESEM) experiment indicated that the plate-like crystallite particles (size 3-10 mm) were precipitated in a mother glass matrix heated at 800 degrees C and restructured into droplet-type morphology when nucleation was supported by Ti4+ ions. The presence of Zr4+ ion results an interlocked type microstructure that is desirable for sealing application because of their capability to resist the growth of a microcrack caused due to thermal stress. A wide thermal expansion value (=11.06 x 10(-6)/K) compatible with SOFC components (electrode, electrolyte, interconnect, and so on) is achieved for Zr4+-doped SiO2-MgO-Al2O3-B2O3-K2O-F glass-ceramic. No considerable deformation in thermal expansion value up to 10 thermal cycling operations is obtained for Zr4+ doped glass and this is ascribed to the interlocked type morphology (FESEM). (C) 2020 Elsevier Ltd. All rights reserved.

Item Type: Article
Subjects: Glass
Divisions: Glass
Depositing User: Bidhan Chaudhuri
Date Deposited: 22 Jan 2021 11:04
Last Modified: 22 Jan 2021 11:04

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